Air filter for polishing machines



April 13, 1948. 5. A1 CROSBY 2,439,596

AIR FILTER FOR POLISHING MACHINES Filed Oct. 2, 1946 5 INVENTOR. Byjlepkezzyg (r0549 Patented Apr. -13,194s

[UNITED {STA-re a 2,439,596 AIR m'ran non romsnmc machines Stephen A. Crosby, Chicago, 111., assignor to Sterling Tool Illinois Products Company, a corporation of Application'october 2, 1946, Serial No. #00585 This invention relates to polishing machines 2 Claims. (01. 51-170) and more particularly to small power driven sanders for use on various structural materials.

The primary object of the invention is to provide an "improved means for filtering the air which is sucked into the machine to cool the driving motor.

The invention is illustrated a preferred em bodiment in the accompanying drawings,

which- Figure 1 is a fragmentary side elevational view.

of a polishing machine embodying'the invention;

door, the air enters the inlet portion of the housing through the upper portion of the door, and this arrangement has'several important advantages over'thegrille type door shown in my earlier patent. When themachinej is used for sanding,

there is usually aconsiderable amount. of fine Y dust near the'rubbing pad, and some of this will be quickly sucked into the filter so as to clog up its lower portion afterbeing operated for a few hours. In thepresent machine, the incoming I cool air is drawn from a stratum considerably Fig. 2 is a fragmentary front elevationalyiew of,

the. door to the air inlet; Fig. 3 is afront eleva tlonal view of the replaceable filter screen; Fig.4

is a sectional view of the door, taken as indicated a at line 4-4 of Fig. 2; and Fig. 5, is a fragmentary sectional'view, taken as indicated at line 5-4 of Fig. 3.

The machine is generally similar to the one shown in my Patent No. 2,395,537,.dated February 26, .1946. A rubbing pad 6 is. supported be neath the housing frame I and is driven with an orbital movement, at high speed, by a vertically disposed electric motor'within the housing. A small fan, not shown, draws air through an'inlet opening at the front of'the machine and discharges it through slots 8 provided at the top of the machine, as shown in my Patent No. 2,395,537. A door frame 9 is provided in the front of the housing and is of substantially rectangular form. In this frame is seated a filter panel necessary limitations above the. one that is heavily laden with dust, and as a result the filter may be used for a much longer period without requiring cleaning or replacement. The shape of the door also" serves to direct the incoming air to all portions of the face of-the filter panel, and it has been found that better circulation is obtained, as the motor actually runs cooler than with the original design.

The foregoing detailed description is given for clearness of understanding only, and no unshould be understood therefrom, for some modifications will be obvious III that is held in position by a specially designed door II which is the novel feature of the present invention. The filter panel is formed of a thin porous fibrous sheet held between two metal wire screens which are held in position by a marginal binding 12. Preferably the screen isprovided with a small tab If, to facilitate its removal from the door frame forcleaning or replacement.

The door ii is hinged below'the frame on a pintle I4, and a torsion spring I! is provided to urge the door upwardly into-closed position. As shown in Fig. 4, the door II is U-rshaped in crosssection, and tapers downwardly and inwardly from an upper opening ll towards the bottom portion of the filter panel. The side portions I'I portions of the panel and hold it in position,- so

" that all of, the air entering the housing must pass through the panel.

' Itwillbenoted'thatbythisconstructionofthe f of the door are adapted to engage the marginal hinged to said frame so as to hold said screen in the door frame, said door having its body portion spaced from the frame and provided with an opening at its top portion to admit incoming air downwardly to the face of said screen.

2. Apparatus as specified in claim 1, in which the hinge is at the bottom of the door and said "door is U-shaped in cross section with its body portion curved downwardly and inwardly towards saidhinge. v

' acmsar.

ncascrrm The following references are of file ofthispatentr nun'a'n s'rA'ras-rsm'rs Number' Name record inthe 1am reamimm 

